<communications, standard> (Formerly "RS-232") The most common
	{asynchronous} {serial line} {standard}.  EIA-232 is the {EIA}
	equivalent of {ITU-T} {V.24}, and {V.28}.

	EIA-232 specifies the {gender} and pin use of connectors, but
	not their physical type.  {RS-423} specifies the electrical
	signals.  25-way {D-type} connectors are common but often only
	three wires are connected - one ground (pin 7) and one for
	data in each direction.  The other pins are primarily related
	to {hardware handshaking} between sender and receiver and to
	{carrier detection} on {modems}, inoperative circuits, busy
	conditions etc.

	The standard classifies equipment as either {Data
	Communications Equipment} (DCE) or {Data Terminal Equipment}
	(DTE).  DTE receives data on pin 3 and transmits on pin 2
	(TD).  A DCE EIA-232 interface has a female connector.  DCE
	receives data from DTE on pin 2 (TD) and sends that data out
	the analog line.  Data received from the analog line is sent
	by the DCE on pin 3(RD).

	Originally DCE was a modem and DTE was a computer or terminal.
	The terminal or computer was connected (via EIA-232) to two
	modems, which were connected via a telephone line.

	The above arrangement allows a computer or terminal to be
	connected to a modem with a straight-through (2-2, 3-3) cable.
	It is common, however, to find equipment with the wrong sex
	connector or with pins two and three reversed, requiring the
	insertion of a cable or adaptor wired as a {gender mender} or
	{null modem}.  Such an adaptor is also required when
	connecting a computer directly to a terminal or to another
	computer without the use of modems.

	(1999-12-28)

1. <networking> A logical channel or channel endpoint in a
	communications system.  The {Transmission Control Protocol}
	and {User Datagram Protocol} {transport layer} protocols used
	on {Ethernet} use port numbers to distinguish between
	(demultiplex) different logical channels on the same {network
	interface} on a computer.

	Each {application program} has a unique port number associated
	with it, defined in /etc/services or the {Network Information
	Service} "services" database.  Some {protocols}, e.g. {telnet}
	and {HTTP} (which is actually a special form of telnet) have
	default ports specified as above but can use other ports as
	well.

	Some port numbers are defined in {RFC 3232} (which replaces
	RFC 1700).  Ports are now divided into: "Well Known" or
	"Privileged", and "Ephemeral" or "Unprivileged" (comprising
	"Registered", "Dynamic", "Private").

	(2004-12-30)

	2. <operating system, programming> To translate or modify
	{software} to run on a different {platform}, or the results of
	doing so.  The {portability} of the software determines how
	easy it is to port.

	3. <language> An {imperative} language descended from {Zed}
	from {Waterloo Microsystems} (now {Hayes} Canada) ca. 1979.

	["Port Language" document in the Waterloo Port Development
	System].

	(2002-06-19)

<body, standard> {Personal Computer Memory Card International
	Association}.  (Or People Can't Memorise Computer Industry
	Acronyms).

(Scientific computation) Output from a computation that may
	not be significant but at least indicates that the program is
	running.  Numbers may be used to placate management, grant
	sponsors, etc.  "Making numbers" means running a program
	because output - any output, not necessarily meaningful output
	- is needed as a demonstration of progress.

	See {pretty pictures}, {math-out}, {social science number}.

	[{Jargon File}]

	(1995-01-13)

<programming> (API, or "application programming interface")
	The interface (calling conventions) by which an {application
	program} accesses {operating system} and other services.  An
	API is defined at {source code} level and provides a level of
	{abstraction} between the application and the {kernel} (or
	other privileged utilities) to ensure the {portability} of the
	code.

	An API can also provide an interface between a {high level
	language} and lower level utilities and services which were
	written without consideration for the {calling conventions}
	supported by compiled languages.  In this case, the API's main
	task may be the translation of parameter lists from one format
	to another and the interpretation of {call-by-value} and
	{call-by-reference} arguments in one or both directions.

	(1995-02-15)

1. The art of debugging a blank sheet of paper (or, in these
	days of on-line editing, the art of debugging an empty file).

	2. A pastime similar to banging one's head against a wall, but
	with fewer opportunities for reward.

	3. The most fun you can have with your clothes on (although
	clothes are not mandatory).

	[{Jargon File}]

	(2003-02-12)

In {object-oriented programming} sending a message to an
	{object} (to invoke a {method}) is equivalent to calling a
	{procedure} in traditional programming languages, except that
	the actual code executed may only be selected at run time
	depending on the {class} of the object.  Thus, in response to
	the message "drawSelf", the method code invoked would be
	different if the target object were a circle or a square.

	(1995-02-16)

A message sent to a {newsgroup} or {mailing list} (may also be
	called "a post") or the act of sending it.  Distinguished from
	a "letter" or ordinary {electronic mail} message by the fact
	that it is broadcast rather than point-to-point.  It is not
	clear whether messages sent to a small mailing list are
	postings or e-mail; perhaps the best dividing line is that if
	you don't know the names of all the potential recipients, it
	is a posting.

	[{Jargon File}]